The application addresses broad challenge area Model organisms for social behavior studies: Identification and development of model organisms that allow for integrative analyses of the genetic, biochemical, physiological, and environmental components of social behavior. RFA-OD-09-00401- GM-102. Recent scientific advances have implicated microbial communities in a broad range of human diseases. This emerging understanding suggests treatment strategies that involve manipulating microbial communities. However, current understanding of the behavior of microbial communities is primitive and does not support the design of strategic interventions. Targeted management of microbial communities will require an integrated understanding of the genetic, biochemical, physiological, and environmental components of social behavior of individuals and of the community as a whole. Such an understanding, in turn, requires a model system that is simple and can be manipulated genetically. This system will provide the foundation for integrative analyses of the genetic, biochemical, physiological, and environmental components of social behavior of microorganisms, including phenomena such as invasion of microbial communities and how communities exclude invaders. The proposed work will develop a system for addressing this knowledge gap in the gut community of the insect, Manduca sexta. In this project, we introduce the concept of "metagenetics," which is the study of the genetic basis for community phenotypes. We will identify genes involved in invasion of the community by Enterococcus faecalis, and determine whether the same genes are involved in exclusion of invaders when E. faecalis is a community resident. We have developed an optical imaging technique to screen luminescent mutants of E. faecalis strain OGR1F, which is a powerful colonist of both human and insect tissue. The long-term goal of this work is to understand the nature of robustness of microbial communities. We will begin to dissect this characteristic using metagenetics, the genetic analysis of community behavior. The model system we will use is the microbial community in the gut of Manduca sexta, the tobacco hornworm. Manduca is a well-established model system in which many physiological discoveries relevant to humans have been made (such as heartbeat reversal). The system provides a simple model in which the principles governing individual and community behavior can be elucidated. As such, our specific aims are to: 1. Identify mutants of Enterococcus faecalis that are defective in gut community invasion. 2. Genetically characterize invasion mutants identified in Aim 1. 3. Characterize behavior of invasion mutants in the Manduca gut microbial community. Innovation: The project's innovation derives from the conceptual framework, which is a new formulation of an old concept - application of genetic analysis to communities. The model system is also innovative, enabling direct quantification of microbial populations with luminescence imaging in live animals. The principles developed through this analysis will be tested ultimately in more complex communities to formulate a general theoretical framework for microbial behavior in communities based on empirical data. Investigator: The investigator is a Howard Hughes Medical Institute Professor who has studied the genetics of microbial ecology for 30 years. She has published significant work in functional metagenomics (and coined the word), host-microbe interactions, microbial interactions, and polymicrobial disease. In addition to her scientific expertise, Handelsman is a skilled mentor who has published and provided national leadership on mentoring. Environment:. Situated in the Department of Bacteriology at the University of Wisconsin, the Handelsman lab has access to sufficient equipment, space, and intellectualism to complete this project effectively. The department recently moved to a well-equipped, modern building that contains 40 microbiology research labs, providing a hub for the more than 100 microbiology faculty at the University of Wisconsin-Madison. Impact:. The work has the potential to profoundly alter the field of microbial community ecology because it provides a new framework for analysis of genotype-phenotype relationships at the community level. The model system may be adapted to other applications and it may provide the basis for deriving predictive models about community behavior in the face of perturbation. Such models are essential to the ultimate goal of manipulating communities for the benefit of human health. PHS 416-1/416-9 (Rev. 9/08) Page Continuation Format Page The work has the potential to profoundly alter the field of microbial community ecology because it provides a new framework for analysis of genotype-phenotype relationships at the community level. The model system may be adapted to other applications and it may provide the basis for deriving predictive models about community behavior in the face of perturbation. Such models are essential to the ultimate goal of manipulating communities for the benefit of human health.